Apparatus for feeding leather to smoothing presses



March 1952 v. KADEAvEK 2,583,845

APPARATUS FOR FEEDING LEATHER TO SMOOTHING PRESSES' Filed Aug. 4, 1949 VIII/l 1 I All f E ES- 55 INVENTOR I ATTORNEYS.

Patented Mar. 11, 1952 OFFICE APPARATUS FOR FEEDING LEATHER TO SMOOTHING PRESSES Vaclav Kadeiavek, GottWaIdOV-Otrokovice, Czechoslovakia, assignor to Svit, naroflni podnik, Gottwaldov, Czechoslovakia Application August 4, 1949, Serial No, 108,467 In Czechoslovakia September 8, 1948 3 Claims. 1

In the existing leather smoothing or pressing machines, the leather is guided by hand to the working space of the press. This operation tedious and very dangerous since the leather has to be straightened out under the press plat and. its position has to be adjusted continuously, if a perfect smoothing or pressing effect is to be obtained all over the surface treated. As a r le, the apacity of the pressing dev ce is no ful y ut used, because the preparatory o rati ns on e leather to be treated require a longer period than the time which is necessary to carry out the smoothin or p ess n oper tion el Accordin ly. attemp s h v en made to ecure by mechanical means the automatic feeding of the leather to the press, but not one of the methods hitherto proposed has proved successful, as the fe ding i s ha n i mplex nature and the control and supervision of the work have been dimcult. The present invention makes it possible to avoid completely the above disadvantages and to accelerate and simplify considerably the control and supervision of the machine and thereby to minimize the losses of time.

The essence of the invention is that the drive of the endless band which conveys the leather to the working space of the smoothing hydraulic press is effected by hydraulic means, the flow of pressure liquid being used for this purpose at the moment when the said pressure liquid has terminated the pressing operation and the press is being opened.

L'Ifhe manner and the means for achieving the desired results are described morejfully in the fol lowing description with reference to the accompanying drawing which shows diagrammatically an example of means for feeding the leather in accordance with the present invention.

The leather is fed to the working space of the smoothing press by means of an apparatus which comprises a valve I, a pipe 2 and a cylinder 3 in which a driving piston 4 with its piston rod 5 .Qperates, the piston rod being extended at one vegrtremil'o' to form a toothed rack 6. The rack 6 engages with a gear wheel I which by means of a ratchet wheel 8 and associated pawls drives a drum 3 and an endless conveyer band I0 guided around the drum. The piece of leather to be treated is placed on the endless band Ill. The

end of the piston rod 5 which projects downwards from the cylinder 3 carries a weight I! while the opposite end portion of the piston rod 5 which projects upwards from the cylinder 3 is provided with ashock absorber 20. An overflow conduit II connected to a pipe I52 serves to equalize the pressure to that prevailing in the supply tank I3 for the pressure liquid as soon as the press has terminated its work. A hand lever I4 is provided for the control of the valve I which in turn controls indirectly an auxiliary piston I5 and a valve I6 associated therewith, the piston I5 and the valve I6 being connected together by means of a draw rod 2i. To insure the co-operation of the two valves I and I 6 they are interconnected by the pipes 2 and I8, and for pressure equalization a pipe I9 is connected to the pipe I2 which leads to the supply tank I 3. The draw rod 2| has a pivotal connection with a lever 22 which, by means of a rod 23, is adapted to lift a valve 24 in association therewith; The valve 24 is so arranged as to out off the connection between the pressure pipe R1, which feeds pressure liquid under the press pistons A and C, and the supply tank I3. The pressure pipe R provides for the continuous direct supply of pressure liquid both to the space under the lifting piston B and through the excess pressure or safety valve 25 to the pressure pipe R1 arranged underneath the press pistons A and C, and also to'the cylinder 3 through the valve I and pipe 2. During the press opening movement which is initiated by unseating the valve I, the valve 26 operates to reduce the pressure exerted by the liquid in the pipe R1 on the valve 24 in orderthat the latter may be lifted more easily whereby a rapid transfer of pressure liquid to the supply tank I3 is obtained. The apparatus so far described operates as follows:

When the press is being opened, the pressure liquid from underneath the lifting piston 33, together with the pressure liquid which is continuously supplied by a pump P to the pipe R from the supply tank I3, flows through the valve I and thence through the pipes 2 and I8 under the valve I6. The pressure liquid thus flowing into cylinder 3 causes the driving piston 4 to move upwards together-with the piston rod 5 and the toothed rack 6. A portion of the pressure liquid which flows at the same time through pipes 2 and I8 under the valve I6 closes the latter. The closin movement of the valve I 6 causes simultaneously the linkage 2|, 22,. 23 to be moved up and thereby opens the valve 2.4 so that pressure liquid flows from the pipe R1 back to the su ply t k 3; But sh rtly before this takes place the operation of the valve begins so as to prepare the necessary conditions for thelifting of valve 24-. The pressure fl d which is contained in the pipe R1 and under th press pistons A and G. exerts ressure on the valve 24, and this pressure does not permit the valve to-be opened under the action of the force used for its normal lifting. For this reason it is necessary to reduce the pressure in the pipe R1 to such a degree that for lifting the valve 24 no greater force is necessary than that required for closing the valve l6. Owing to the excess pressure of the liquid in the pipe R1, the valve 26 is opened and the pressure liquid escapes past the same until the valve 24 opens.

When the piston 4 is moving up, the rack 6 is in engagement with the gear wheel I which, by means of the pawls and ratchet wheel 8, rotates the drum 9 so that the endless conveyor band travels in the direction of the arrow shown in the drawing.

Between the piston rod and the rack 6 a shock absorber 20 is preferably arranged to absorb the first impact of the pressure liquid against the piston 4, when the endless band 10 is not yet enclosed within the working space of the press.

The advance of the conveyor band can be adjusted in such a way as to move the leather always within the working width of the press plate. When the leather is displaced to this extent, the piston 4 is raised above the overflow conduit H, so that the pressure liquid admitted into the cylinder 3 is free to flow back through the overflow conduit H into the pipe 12 and thence to the supply tank l3. As has been men'- tioned, the piston 4 occupies its upper end position shown in dotted lines and the conveyor band is stationary.

When the valve 1 has been closed by means of the hand lever It, the pressure of the liquid in the pressure pipe R begins to build up due to the constant supply of pressure liquid by the pump P. The piston B then moves up together with the press pistons A and C, so that the press is closing, pressure liquid flowing under the press pistons A and C from the supply tank 13 through the open valve 24. When the working faces of the press have been brought in contact, the increase of the pressure in the pipe It continues until it overcomes the resistance of the safety valve 25. At the same time the higher liquid pressure causes the auxiliary piston 15 to move down whereby the valve I6 is opened. The opening of the valve [6 causes the draw rod 2i and lever 22 to move the rod 23 in downward direction, whereby the valve 24 is closed. Then the pressure liquid flows under increased pressure under the pistons A and C, thereby generating a powerful pressure on the leather under treatment.

During the described working process, the pressure under the piston 4 is removed after valve I has been closed and valve it has been opened. Under. the action of the weight H the piston 4 moves down in the cylinder 3 so that the liquid contained in the cylinder under the piston 4 is driven through the pipes 2 and 18, the open valve [6 and the pipes l9 and 12 into the supply tank l3, and throughthe pipes I9, l2 and the overflow conduit H into the cylinder 3 above the piston 4 to accelerate the fall of the latter in the cylinder 3.

During the downward movement of the piston 4, the rack 6 which also is moving down rotates the gear wheel 1 inthe opposite direction and the pawls slide idly over the teeth of the ratchet wheel 8 so that the conveyorband l0 remains stationary.

When the press is opened again, the above described operations are repeated with concurrent advance of the endless conveyor band.

As it appears from the foregoing description, in the apparatus according to the present invention the manuel operations are limited to the placing of each subsequent leather piece upon the endless conveyor band as soon as the treatment of the preceding piece has been terminated, and to the actuation of the hand lever M for controlling the valve 1, while the operation for feeding the leather to the working space of the press is effected in a fully automatic way.

The working process is quite safe since any irregularities of the leather may be evened by the assistant when the leather is still located on the endless conveyor band while hitherto this operation has had to be made directly in the working space of the press.

What I claim is:

1. An apparatus for feeding leather to a hydraulic press for smoothing and pressing the same in which the feeding of the work pieces takes place after a preceding pressing operation and coincident with opening of the press, said press including press cylinders having pistons therein for operating the press, a fluid reservoir, a fluid supply line for flow of fluid between said reservoir and said press cylinders, a cut-off valve in said supply line adapted when seated to cut off return now of fluid from the press cylinders to said reservoir, a pressure fluid line, a pump for supplying pressure fluid from said reservoir to said pressure fluid line, a conveyor band for the work pieces, driving mechanism for advancing the conveyor band step-by-step through the press, a hydraulic cylinder, a piston in said cylinder connected to actuate said driving mechanism, an inlet connection from said pressure fluid line to one end of said hydraulic cylinder, a manually controlled valve in said inlet connection, an outlet connection from adjacent the other end of said hydraulic cylinder positioned to be uncovered by travel of the piston to said end, a fluid return line connecting said outlet connection to said fluid reservoir, a connection from said pressure fluid line to the fluid supply line for the press cylinders between the latter and the cut-oif valve, a spring loaded one-way excess pressure valve in the last mentioned connection, an auxiliary piston exposed to the pressure in said pressure fluid line, a spring biased valve connected to said auxiliary piston, a by-pass from the inlet connection to said hydraulic cylinder to the underside of said spring biased valve and from the other side thereof to said return line, the bias on said valve being such that said valve is opened when the manually controlled valve is closed, and vice versa, actuating connections between said auxiliary piston and the cut-off valve in the supply line between the fluid reservoir and the press cylinders so arranged that when the auxiliary piston is depressed by the pressure fluid the cutoff valve is closed, a relief valve communicating with the pressure fluid line for relieving the pres.- sure above said cut-off valve when the manually controlled valve is opened, whereby to permit the cut-off valve to be opened by the pressure acting to close said spring biased valve.

2. The apparatus as set forth in claim 1, wherein a shock absorber is provided between the rod of the piston in said hydraulic cylinder and a rack bar operated by said piston to drive the feeding mechanism of the conveyor band, and a counterweight urging the said piston downwards to discharge liquid from the hydraulic cylinder back through the inlet connection thereto and thence through the by-pass to the return line when said manually controlled valve is closed.

3. The apparatus defined in claim 2, wherein a press-closing cylinder and piston of lesser volume than said press cylinders is connected to said pressure fluid line to efiect a quick closing of the press upon closing of the manually controlled valve.

vAcLAv KADERAVEK.

REFERENCES CITED The following references are of record in the file of this patent:

Number UNITED STATES PATENTS Name Date Voss Mar. 17, 1914 Voss Nov. 7, 1916 Bredenberg July 27, 1926 Franzen et a1 June 18; 1935 Schwartz June 16, 1942 Muller Oct. 10, 1944 

